Cracking with catalyst having controlled residual coke



J. w. PAYNE ET AL CRACKING WITH CATALYST HAVING CONTROLLED RESIDUAL COKE2 Sheets-Sheet Filed Jung 28, 1965 LIFT PIPE

ACCOLERV REGENERATOR HEAT EXCHANGER STRIPPER' PRODUCT- COOLER //V l/E/VTORS John 14 Payne Robe/l A. Sailor F/GJ,

Jerome Farber.

-Nov. 7, 1967 J"W PAYNE ET-AL 3,351,548

CRACKING WITH CATALYST HAVING CONTROLLED RESIDUAL COKE Filed June 28, 1965 2 sheets -sheet 2 f( 60 -if% 1 2 15i /06 '70 74 GAS "",/04 AIR FEED72 //0 A /02 LIFT m8 Z5 /P|PE REGENERA'TOR VCRACKERU PRO CT #6 I 80 ouFLUE *f GAS HEAT EXCHANGER and STRIPPER //Vl /VTO/?5 7 John W Payne FLUEHaber/ASai/or GAS Jerome Farber GAS Age

United States Patent Ofiice 3,351,548 CRACKING WITH CATALYST HAVINGCHNTROLLED RESIDUAL (IOKE John W. Payne, Woodbury, Robert A. Sailor,Cinaminson, and Jerome Farther, Cherry Hill, N.J., assignors to MobilGil Corporation, a corporation of New York Filed June 28, 1965, Ser. No.467,321

2 Claims. (Cl. 208-420) This invention relates to the conversion ofhydrocarbons in the presence of finely divided solid particle materialhaving cracking activity. More particularly, the invention relates tothe method for cracking hydrocarbons in the presence of an activealumino-silicate cracking component having an initial activitysubstantially above that obtainable with an amorphous silica-aluminacatalyst. In another aspect, the present invention is concerned with themethod of operating a catalytic conversion-regeneration system atsubstantially elevated temperatures in the presence of a catalyst ofcontrolled activity.

In the cracking of hydrocarbons using the fluidized catalytic crackingtechnique, the catalyst in the form of a fine powder is circulatedthrough a reaction-cracking zone and then through a regeneration zonefor the removal of carbonaceous material deposited on the catalystduring the cracking step. The removal of carbonaceous material byburning heats the catalyst to an elevated temperature suitable forrecycle to the regeneration step and use in the cracking step. Theamount of catalyst recycled to the hydrocarbon conversion step isgenerally quite large in fluid systems, being in a range of from about 5to about 20 times the amount of oil passed to the conversion step on aweight basis and is usually in a quantity sufficient to supply a largeportion, if not a major portion of the reaction heat required in theconversion step.

In the catalytic cracking of hydrocarbon oils utilizing the fluidcatalyst technique, one of the major problems in such an operation isconcerned with regeneration of the catalyst. Regeneration of thecatalyst is accomplished by burning carbonaceous deposits from thecatalyst with air or oxygen supplemented gaseous material in one or moreseparate regeneration vessels. Accordingly, the spent catalystcontaining deposited carbonaceous material is continuously supplied to aregeneration zone of a sufficient size which can become quite enormousdepending upon the quantity of cokey material to be burned. For example,coke burned quantities of the order of about 20,000 and as high as50,000 pounds of coke per hour are not uncommon in the industry.Therefore, the coke removal from catalyst particles of these magnitudesin a relatively short length of time, has in the past requiredrelatively large and expensive regenerator equipment. Generally theregeneration system holds a major portion of the total catalystinventory in the catalytic cracking-regeneration system.

In the method and system of this invention, many of the above mentionedand undesired factors have been taken into account so that catalystinventory, equipment size and actual cost could be significantly reducedfor the conversion of the quantity of hydrocarbon feed equal to or abovethat previously required in prior art systems.

An object of this invention relates to providing an improved system forthe conversion of hydrocarbons in the presence of catalytic materialhaving a high activity cracking component.

Another object of this invention relates to providing a system for theconversion of hydrocarbons in the presence of a cracking catalystcomprising a catalytically active crystalline alumino-silicate.

A further object of this invention relates to the method of convertinghydrocarbons in a dispersed phase catalytic cracking regeneration systemwherein the catalyst inven- 3,351,548 Patented Nov. 7, 1967 tory andregeneration heat output are significantly below that normally produced.

Other objects of this invention will become more apparent from thefollowing discussion.

This invention relates to forming a dilute suspension of granularcatalyst containing residual coke in hydrocarbon vapors at a temperatureof at least about 800 P. which suspension is then passed through anelongated reaction zone under conditions to achieve at least about 50%conversion of fresh feed. Spent particles are separated from hydrocarbonvapors and combined with sufficient freshly regenerated catalyst to forma mixture at a temperature of at least 1000 F. and thereafter thecatalyst is regenerated under conditions to retain up to about 1.0% byweight, more usually up to about 0.5% by weight of residual coke. Thecatalyst is thus regenerated and under conditions not to exceed heatdamaging temperatures or temperatures substantially above about 1500 F.

In a more specific embodiment, the present invention relates to themethod and system for upgrading gas oil and higher boiling hydrocarbonsby conversion thereof in the presence of a catalytic material of aparticle size avoiding substantial undesired diffusion limitations andcomprising an activity monitored crystalline aluminosilicate incombination with selective regeneration of the catalytic material in oneor more catalyst contact zones. The contact zones may be in parallel orsequential hydrocarbon fiow arrangement for effecting catalytic crackingof hydrocarbons and sequential catalyst flow arrangement forregeneration of the catalyst employed in the conversion steps.

The method and systems of this invention relate to a combination ofprocessing steps which permits a limited and desired removal ofcarbonaceous material from the hydrocarbon conversion catalyst in one ormore regeneration steps by an amount previously determined to maintainthe activity of the catalyst within a desired range. Thereafter the thusregenerated catalyst is used for the conversion of hydrocarbons at acatalyst-oil ratio significantly lower than that generally employed inthe prior art processes to achieve a conversion of fresh feed of atleast 50% and as high as about 65%.

The catalysts useful in a present invention are those comprisingcatalytically active crystalline alumino-silicates which have an initialrelatively high activity substantially above that attributable to anamorphous silicaalumina catalyst and maybe catalysts such as describedin copending application Ser. No. 208,512, filed July 9, 1962. It hasbeen found as a result of considerable experimental evidence that thecatalyst comprising crystalline alumino-silicates in a catalyticallyactive form are advantageous in view of product selectivity obtained bytheir use. It has also been noticed that when properly controlled, thegasoline yield to coke make in gas oil cracking has been verysubstantially more attractive than that obtainable with a moreconventional cracking catalyst. Accordingly, the crystallinealumino-silicate catalysts suitable for use in the method and system ofthis invention are materials of ordered internal structure in whichatoms of alkali metal, alkaline earth metal, or metals in replacementthereof are arranged in a definite and consistent crystalline or orderedpattern. These structures in one form or another contain a large numberof small cavities interconnected by a number of still smaller openings.However, these cavities and openings are precisely uniform in size. Theinterstitial dimensions of openings in the crystal lattice of some ofthe zeolites limit the size and shape of a molecule (hydrocarbon) thatcan enter the interior of the alumino-silicate and it is suchcharacteristics of crystalline zeolites that has led to theirdesignation Molecular Sieves.

Zeolites having the above characteristics include both natural andsynthetic materialsfor example, chabazite,

gmeilinite, mesolite, ptiliolite, mordenite, natrolite, nepheline,sodalite, scapolite, lazurite, leucrite, and cancrinite. Syntheticzeolites may be of the A type, X faujasite type, Y faujasite type, Ttype, or other well known form of molecular sieve including ZK zeolitessuch as those described in copending application Ser. No. 134,841 filedAug. 30, 1961, now Patent No. 3,314,752. Preparation of zeolites of someof these types is well known, having been described in the literatureforexample, A type zeolite in U.S. 2,882,243; X faujasite type zeolite inU.S. 2,882,- 244; other types of materials in Belgium Patent No. 577,-642 and in U.S. 2,950,952. As initially prepared, the metal of thealumino-silicate is an alkali metal usually sodium. Such alkali metal issubject to base-exchange with a wide variety of other metal ions. Themolecular sieve materials so obtained are usually porous, the poreshaving highly uniform molecular dimensions, generally between about 3and possibly about 15 Angstrom units in diameter. Each crystal ofmolecular sieve material contains literally billions of tiny cavities orcages interconnected by openings of unvarying diameter. The size,valence, and amount of the metal ions in the crystal can control theeffective diameter of the interconnecting channels.

At the present time, there are commercially available materials of the Aseries and of the X faujasite series. A synthetic zeolite known asMolecular Sieve 4A is a crystalline sodium alumino-silicate havingopenings of about 4 Angstroms in diameter. In the hydrated form, thismaterial is chemically characterized by the formula:

Na (AlO 12(SlO2)12.27H2O The synthetic zeolite known as Molecular Sieve5A is a crystalline alumino-silicate salt having openings about 5Angstroms in diameter and in which substantially all of the 12 ions ofsodium in the immediately above formula are replaced by calcium, itbeing understood that calicum replaces sodium in the ratio of onecalcium for two sodium ions. A crystalline sodium alumino-silica havingpores approximately Angstroms in diameter is also available commerciallyunder the name of Molecular Sieve 13X. The letter X is used todistinguish the interatomic structure of this zeolite from that of the Acrystals mentioned above. As prepared, the 13X material contains waterand has the unit cell formula:

sal 2)ss( 2)10sl 2671-120 The 13X crystal is structurally identical withfaujasite, a naturally occurring zeolite. The synthetic zeolite known asMolecular Sieve 10X is a crystalline alumino-silicate salt havingopenings about 10 Angstroms in diameter and ill which a substantialproportion of the sodium ions of the 13X material have been replaced bycalcium.

Molecular sieves of the X faujasite series are characterized by theformula:

se/nl 2) M 2 106] 2 Where M is Na+, Ca+-|- or other metal ionsintroduced by replacement thereof and n is the valence of the cation M.The structure consists of a complex assembly of 192 tetrahedra in alarge cubic unit cell 24.95 A. on an edge. Both the so-called X and theso-called Y type crystalline .alurnino-silicates are faujasites and haveessentially identically crystal structures. They differ from each otheronly in that type Y alumino-silicate has a higher SiO /AI O ratio thanthe X type alumino-silicate.

The alkali metal generally contained in the naturally occurring orsynthetically prepared zeolites described above may be replaced by othermetal ions. Replacement is suitably accomplished by contacting theinitially formed crystalline alumino-silicate with a solution of anionizable compound of the metal ion which is to be zeoliticallyintroduced into the molecular sieve structure for a sufficient time tobring about the extent of desired introduction of such ion. After suchtreatment, the ion exchanged product is water washed, dried andcalcined. The extent to which exchange takes place can be controlled. Itis essential that the aluminosilicate undergoing activation be a metalcontaining alumino-silicate.

Naturally occurring or synthetic crystalline aluminosilicates may betreated to provide the superactive aluminosilicates employed in thisinvention by several means, such as base exchange to replace the sodiumwith rare earth metal compounds, by base exchange with ammoniumcompounds followed by heating to drive off NH ions, leaving an H or acidform of alumino-silicates by treatment with mineral acid solutions toarrive at a hydrogen or acid form, and by other means. These treatmentsmay be followed by activity-adjusting treatments, such as steaming,calcining, dilution in a matrix and other means. Explanation of themethods of preparing such catalysts is made in copending applicationSer. No. 208,512, filed July 9, 1962, now abandoned.

It should be noted that the catalyst used in this invention may be acomposite of the superactive aluminosilicate and a relatively inertmatrix material, it may be a mechanical mixture of superactive materialparticles and matrix material particles, or it may consist only of thesuperactive catalyst. If the catalyst consists of a composite, it may beproduced in the form of relatively small granules. The matrix materialmay be any hydrous oxide gel, clay or the like. The matrix material usedmust have a high porosity in order that the reactants may obtain accessto the active component in the catalyst composite. A high porositymatrix of the hydrous oxide type may be used in these compositecatalysts, such as silica-alumina complexes, silica-magnesia, silicagel, or high porosity clay, alumina, and the like.

The systems of this invention and methods of operation will be morespecifically described with reference to the accompanying drawings. Thedrawings illustrate diagrammatically the major components of the systemsand will be described in conjunction with an arrangement designed toprocess about 30M b.p.d. (30,000 barrels per day), of gas oil feed at asingle pass conversion level up to about 65%. By percent conversion wemean volume of insufficiently converted material boiling above gasolineboiling material.

In the arrangement of FIGURE I, the catalyst with hydrocarbon feed orregeneration gas is introduced to the bottom or lower portion of a lifttype contact zone through which the catalyst is passed in a relativelydispersed phase condition. Velocities above about 5 feet per second fora contact time in the range of from about 1 to about 30 seconds are usedand under conditions which avoid unstable flow of catalyst through thecontact zones. Generally, the velocities employed in the conversion zonewill be maintained as low as possible, in the range of from about 10 toabout 50 feet per second, and high enough to avoid unstable catalystflow conditions. In the method of this invention it is preferred toemploy low catalyst to oil ratios in the range of from about 2 to about4 pounds of catalyst per pound of oil in the dispersed phase conversionzone under conversion inlet temperature conditions generally above about900 F. and preferably at least about 950 F. but below about 1050 F.Under these conditions employing a temperature of at least about 900 F.a conversion per pass up to about 60% and preferably about 65% will beobtained of the gas oil feed.

By unstable catalyst flow is meant a condition of cata lyst refluxingresulting in excessive catalyst attrition, and/ or excess erosion ofequipment when operating with finely divided solid particle material. Itis preferred in the method and system of this invention to employ aparticle size sufficiently small to be suspended in a gasiform materialand sufiiciently small to avoid undesired diffusion limitations withrespect to the cracking and regeneration operations but large enough toflow with mechanical aids. Accordingly, it is preferred to employ acatalyst particle size falling in the range of from about 60 to aboutmesh size and/or mixtures thereof since particle material in this sizerange pours relatively freely and handles in a manner similar togranular contact material.

The catalyst particles recovered from products of conversion andseparated from the dispersed phase conversion zone are passed throughone or more controlled stages of catalyst regeneration maintained underconditions to eifect a limited removal of deposited carbonaceousmaterial from the catalyst particles in any one stage. It is proposed toretain on the catalyst particles from about 0.1% to about 0.5% weight ofresidual coke. The coke retained on the catalyst particles has beensuccessfully employed to snub the initial relatively high activity ofalumino-silicate containing catalyst of the type herein describedWithout substantially reducing the activity to an undesired level. Inaddition, the regeneration technique employed in accordance with thisinvention permits operating under conditions and in a manner providingsignificantly higher burning rates per unit volume of regeneratorcapacity thereby significantly contributing to reduced regenerationcosts and equipment.

The burning rates obtainable in the method and systems of this inventionare further enhanced by maintaining the regenerator system underelevated pressure condi tions. However the pressure relationship betweenthe reactor and regenerator should be selected which will avoid undulylong seal legs therebetween. It is significant that elevated pressuresin the hydrocarbon conversion section can also be used to advantage forcausing separated hydrocarbon conversion product vapors to pass from thehydrocarbon conversion zone to and through suitable product recoveryequipment. Therefore, it is contemplated employing pressures in theregenerator-conversion sections sufiiciently above atmospheric pressureto cause flow of hydrocarbon products from the conversion zone up toabout 100 p.s.i.g. and preferably pressures of at least about p.s.i.g.

The regeneration section of the system herein described and its methodof operation departs rather significantly from the prior art since itincludes among other things the recycle of a portion of the hotregenerated catalyst at substantially its maximum temperature to theinlet of the regeneration section in admixture with spent catalystrather than the recycling of cooled regenerated catalyst as is wellknown in the prior art. That is, the regeneration technique hereinemployed includes the mixing of a sufficient excess of hot regeneratedcatalyst with spent catalyst recovered from the hydrocarbon conversionstep to obtain a mixed catalyst temperature of at least about 1000 F.and preferably at least about 1150 F. It is preferred, therefore,whether employing one or more dispersed phase regeneration zones tolimit the upper temperature of the catalyst particles to about 1300 F.even when employing a catalyst mixed temperature passed to the inlet ofthe regenerator in the range of from about 1150 F. to about 1200 F. In aspecific embodiment it is contemplated mixing of the order of about 3volumes of hot regenerated catalyst containing residual coke thereonwith about 1 volume of catalyst recovered from the hydrocarbonconversion step to provide a mixture having a temperature of about 1200F. The thus formed catalyst mixture is passed to the inlet of theregeneration section and subjected to coke burning conditions in thepresence of an oxygen containing gas stream. The catalyst to beregenerated may be passed through a plurality of dispersed phase cokeburning zones in the presence of an oxygen containing gas and maintainedunder conditions limiting the temperature rise encountered in any onezone below about 100 so that an upper catalyst temperature of about 1500F. will not be exceeded. The regenerated catalyst with residual cokeremaining thereon of a desired range is recovered from the regenerationsection at a temperature not substantially above about 1500 F. andpreferably not substantially above about 1300 F. The recycledregenerated catalyst serves a dual function in the method of thisinvention which includes providing a desired regenerator inlettemperature and the absorption of heat during burning of cokey depositson the catalyst particles.

As suggested herein the system and method of operation of this inventionmay be regarded as a heat deficient operation because of the catalystselectively employed therein. The hydrocarbon conversion conditionsemployed limits the coke on catalyst from the conversion operation thatis available to heat the catalyst during regeneration to a desiredregeneration temperature. However, by mixing a sufficiently large volumeof hot regenerated catalyst with a desired amount of preheated and cokedcatalyst particles obtained from the conver sion zone under suitablecondition, the regeneration section inlet temperature will besufiiciently elevated to permit achieving a desired high burning rate.To accomplish the above, it was found that the spent conversion catalystshould be heat exchanged indirectly with regeneration catalyst to raisethe temperature of the spent catalyst sufficiently so that when it ismixed with the hot regenerated catalyst a mixed temperature of about1200 F. is obtained. Stripping of the spent conversion catalyst ofentrained hydrocarbon vapors can be accomplished also dur ing theindirect heat exchange step. Accordingly, an inert gaseous material isemployed to remove varporizible hydrocarbons from the catalyst separatedfrom the dispersed phase hydrocarbon conversion zone and this strippingmay be accomplished separately or during the indirect heat exchange stepas discussed above.

Having thus provided a general description of the improved method andsystems of this invention, reference is now had to the drawing by way ofexamples which show specific arrangements of up flow and down flowdilute phase catalyst contact sections for practicing the method of thisinvention.

FIGURE 1 diagrammatically represents in elevation an arrangement ofapparatus comprising a system for practicing the method of thisinvention in a dispersed phase elongated up flow confined contact zones.

FIGURE 2 diagrammatically represents in elevation an arrangement ofapparatus comprising a system for practicing the method of thisinvention which includes dispersed phase down flow contact zones.

FIGURE 3 presents diagrammatically a modification of the contact zonesof FIGURE 2 directed to countercurrent impingement contact of reactantand solid particle material.

Referring now to FIGURE 1 by way of example, an arrangement of apparatusis shown comprising an elongated up flow dilute phase confinedconversion zone 2 or lift pipe discharging into a separation zone 4 forseparating finely divided granular solid contact material from vaparousmaterials such as vaporous hydrocarbon product material obtained in theconversion step. It is contemplated employing in the arrangement ofFIGURE 1 more than 1 elongated confined reaction zone or lift pipe insubstantially parallel flow arrangement for freshly regeneratedcatalytic contact material and sequential flow of insufficientlyconverted hydrocarbon material. Accordingly, the hydrocarbon conversionproducts of one conversion stage may be separated in suitable equipmentincluding a product fractionat-or to recover material boiling abovegasoline boiling hydrocarbons which higher boiling material are passedthrough the second stage of hydrocarbon conversion. That is, anarrangement comprising parallel catalyst flow conversion zones may beempioyed under conditions for completing conversion in one zone theinsufliciently converted hydrocarbons separated from the products ofconversion in the adjacent hydrocarbon conversion stage. The hydrocarbonconversion products obtained in the conversion section are passed to andthrough suitable product recovery processing equipment not shown.

In the specific arrangement and embodiment of FIG- URE l, a hydrocarbonfeed such as a gas oil boiling range hydrocarbon feed, is introduced byconduit 8 into a vaporous hydrocarbon catalyst engaging or contactingzone 6 positioned at the bottom of an elongated conversion zone or liftpipe 2. The hydrocarbon feed is heated to a sufficiently elevatedtemperature of the order of about 915 F. before entering zone 6.Regenerated catalyst containing a desired amount of residual cokeaveraging about 0.25% by weight is passed by conduit 10 to the engagingzone 6 wherein a dispersed suspension of catalyst in hydrocarbon vaporsis formed and passes upwardly through the conversion lift pipe. In themethod of this invention a suspension having a catalyst to oil ratio ofabout 2:1 and at a mixed inlet temperature at about 950 F. is thereafterpassed upwardly through the elongated confined lift pipe conversion zone2. at a velocity sufficiently high to avoid undesired flow conditionsbut suflicient to provide a catalyst particle residence time of about 7seconds. To accomplish the above conversion of hydrocarbon feed andobtain a single pass conversion of the order of about 65%, it is foundthat an elongated lift pipe about 6 feet in diameter and approximately97 feet high is sutficient to provide the desired hydrocarbon-catalystcontact time. In this specific embodiment and operating under the aboveconditions, a catalyst composition is used comprising about 50% rareearth exchange Y type crystalline alumino-silicate combined with asuitable inert binder material to form granular particles of a desiredsize. A suspension comprising product vapors, insufficiently convertedhydrocarbons and catalyst particles is discharged from the elongatedconversion zone at a elevated temperature at about 880 F. into asuitable separation zone 4. Since the particle size of the catalyticcontact material employed is in the range of from about 60 to about 150mesh size, elaborate cyclone separator equipment can be substantiallyavoided to achieve suitable separation and recovery of catalystparticles from hydrocarbon vapors. Accordingly, separation zone 4 may beone or more sequentially connected cyclone separators which willeffectively achieve the desired separation of catalyst particles fromthe hydrocarbon conversion product vapors. Hydrocarbon vapors thusseparated and substantially free of entrained catalyst particles areremoved from the upper portion of the separation zone 4 by conduit 12.The catalyst particles separated and recovered from the suspensionintroduced to separator 4 are removed from the lower portion of theseparation zone 4 by conduit 14 and passed to a suitable heatexchanger-stripping zone 16. Zone 16 diagrammatically represents meansfor passing hot regenerated catalyst in indirect heat exchange withcatalyst particles recovered from the hydrocargon conversion step. Inconjunction with this heat exchange step, it is contemplated providingfor stripping of the catalyst with a suitable relatively inert strippinggas to effect more complete removal of any entrained and adsorbedvaporous hydrocarbons remaining with the catalyst particles.Accordingly, the function of zone 16 comprises cooling of regeneratedcatalyst to a desired lower temperature by giving up heat to the spentor used catalyst passing therethrough before the spent stream ofcatalyst enters the regeneration section. As suggested above, heating ofthe used or spent catalyst before entering the regenerating zone isaccomplished to provide a necessary and desired temperature level in thesystem. The stripping gas in indirect heat exchanger 16 also agitatesthe catalyst thereby improving heat exchange and horizontal fiow ofcatalyst therein.

In the event that zone 16 does not accomplish suflicient cooling of theregenerated catalyst prior to entering the conversion section, thecatalyst may be passed by conduit 18 to an additional cooling stepidentified as cooler 20. In cooler 20 the catalyst is cooled to atemperature more suitable for mixing with the hydrocarbon feedintroduced to the inlet of riser 2. In the system of FIGURE 1 it isdesired in one preferred embodiment to employ catalyst inlettemperatures to zone 6 not substantially above about 1000 F. and thecatalyst cooling steps 16 and 20 when employed together are sufiicientto provide desired optimum temperatures. It is contemplated in anotherembodiment, however, of passing the catalyst in conduit 44 at theelevated regeneration temperature directly to zone 6 thereby by-passingzones 16 and 20.

The contaminated catalyst stripped and subjected to preheatingconditions in zone 16 raises the temperature of this catalyst stream toabout 900 F. and is thereafter passed by conduit 22 to a mixer Zone 24.In mix zone 24, the contaminated catalyst is intimately mixed with asufficient quantity of freshly regenerated catalyst introduced theretoby conduit 30 to provide a catalyst mixture having a temperature ofabout 1200 F. Generally, the quantity of freshly regenerated catalystcombined with the contaminated catalyst will be about three-fold greaterin order to obtain a desired mixed temperature sufficiently elevated forintroduction to the inlet of the regenerated section. In the specificembodiment of FIGURE 1 approximately 1163 tons per hour of regeneratedcatalyst is combined with about 3 87 tons per hour of 900 F. spentcatalyst to provide approximately 1550 tons per hour of 1200 F. catalystgoing to the inlet of the regenerator. In order to obtain desired mixingand adjustment of the catalyst temperature, it is proposed to maintainthe catalyst in mixing zone 24 in a relatively dense boiling bedcondition prior to withdrawal of the catalyst by conduit 32 for passageto engaging zone 34 at the inlet of the regeneration zone 40. In oneembodiment of this invention it is contemplated employing a plurality ofrelatively dispersed phase regeneration zones arranged for sequentialflow of catalytic material therethrough to provide a desired residencetime and controlled removal of carbonaceous deposits from the catalystby burning in an oxygen containing atmosphere. Accordingly, it isproposed to effect the dispersed phase regeneration of the catalyst atvelocities of at least about 10 feet per second and preferably at leastabout 20 feet per second. In any event, whether one or more stages ofregeneration is employed, the regeneration of the catalyst is to beconducted with an oxygen containing gas introduced to the inlet of eachregeneration stage by a conduit similar to conduit 36. Furthermore, asdiscussed hereinbefore regeneration of the catalyst is to be effectedunder conditions which leave a desired residual quantity of coke on thecatalyst particles so that the catalyst passed to the inlet of thehydrocarbon conversion stage will have in one specific embodiment anaverage value of about 0.25% by weight residual coke on the catalyst.The regenerated catalyst whether passed through one or a plurality ofstages of dilute phase regeneration is separated from regeneration fluegas at an elevated temperature of about 1300 F. in a suitable separationzone such as zone 33 of FIGURE 1. It is to be understood that separationzone 38 may comprise one or more suitably connected cyclone separatorsfor the recovery of regenerated catalyst from regeneration flue gases.The separated flue gas is thereafter removed from separator zone 38 byconduit 42. The regenerated catalyst collected in the lower portion ofseparator 38 is withdrawn in desired quantities for passage to mix zone24 and mix zone 16 by conduits 26 and 44 respectively. This thencompletes the circulation of catalyst particles within this system in amanner which permits converting hydrocarbons in accordance with at leastone method of this invention.

In the event that the regenerated catalyst withdrawn by conduit 26 is atan elevated temperature higher than that desired for introduction to mixzone 24 a cooler 28 is provided to reduce the temperature of therecycled regenerated catalyst to a desired level before being passed byconduit 30 to mix zone 24. By desired is meant the temperature, whichwhen mixed with the spent catalyst results in a mixed temperature ofabout 1200 F. The amount is the quantity which will hold the temperaturerise in the regenerator to about F.

FIGURE 2 on the other hand, although suitable for accomplishing thehydrocarbon conversion operation thus described with respect to FIGURE1, differs therefrom by the use of a dispersed phase down flowhydrocarbon conversion zone; the use of inert gas such as flue gas tolift regenerated catalyst to the upper portion of the hydrocarbonconversion zone; and a down flow dispersed phase regenerated zone isused in combination with an up flow dispersed phase regeneration stage.In the system of FIG- URE 2 an oxygen containing lift gas such as air isintroduced by way of conduit 50 to mix zone 52 wherein preheated spentor contaminated catalyst is introduced by conduit 54 and hot regeneratedcatalyst is introduced by conduit 56 to form a mixture of catalystparticles having a temperature of about 1100 F. Thereafter theregeneration gas containing catalyst particle-s dispersed therein ispassed upwardly from mix zone 52 through the elongated up flow dilutephase regeneration zone 58 under conditions to effect at least partialregeneration of the catalyst therein. The suspension of gaseousmaterials and catalyst passing upwardly through regenerator 58 ispermitted to attain an incremental temperature rise less than about 100F. before being discharged into separation zone 60. The partiallyregenerated catalyst is separated from flue gas in separator 60 andseparated flue gas is removed from the upper portion thereof by conduit62. Separation zone 60 may comprise a plurality of suitably connectedcyclone separators for the separation of solid particle material fromgaseous material.

The partially regenerated catalyst at an elevated temperature of theorder of about 1200" F. is introduced to the top of a second stageregeneration zone 66 and thereafter caused to shower down through thezone in a relatively dilute phase conditioned by a catalyst distributorarrangement across its upper cross section. The distributor comprises aplurality of open end vertically positioned passageways 68. Thepassageways extend through a regeneration gas distributor or plenumchamber 70 also positioned in the upper portion of the regeneration zoneadjacent the catalyst distributor means. A partition member or meansforming the lower portion of the plenum chamber is a foraminous orperforated baflle member containing openings 72 through which regeneration gas is passed after introduction to the plenum chamber byconduit 74. The thus introduced regeneration gas contacts the catalystparticles discharged from the bottom open end of passageways 68. Thethus discharged partially regenerated particles in admixture with anoxygen containing regeneration gas are maintained under elevatedtemperature regeneration conditions during dispersed phase down flow tothe lower portion of the regeneration zone.

Positioned in the lower portion of the regeneration zone is a flue gasrecovery means 76 provided for separating regeneration flue gas fromsolid particle material. The flue gas recovery means 76 may besubstantially any suitable equipment arrangement or means which willeliectively recover particles of a size in the range of 60-150 mesh fromthe recognition flue gases. The separator means 76 specifically shownincludes a conical deflector bafiie means 78 arranged in a manner todeflect catalyst particles from a separator 76 positioned therebelow.This arrangement will be effective in obtaining the separation of solidparticle material from gaseous material prior to the gaseous materialbeing removed from separator means 76. It is to be understood thatseparator means 76 may comprise a plurality of suitably arranged cycloneseparators. Flue gas is Withdrawn from separator means 76 by conduit 80.The solids separated from the flue gas by baflle 78 and separator means76 are collected in the bottom lower portion of the regeneration zone asregenerated catalyst particles for future use in the process as hereindescribed. In accordance with this invention the regenerated catalystparticles contain residual coke thereon and are at elevated temperatureof the order of about 1300" F. brought about by burning a portion of thedeposited cokey material on the catalyst particles. A portion of thethus obtained hot regenerated catalyst particles is withdrawn from thebottom of the regeneration zone by conduit 82, cooled in cooler 84 ifdesired, and thereafter passed by conduit 56 to an engaging zone 52.Another portion of the regenerated catalyst comprising another portionthereof is passed by conduit 86 to an indirect heat exchanger 88. Heatexchanger zone 88 may be similar in function to zone 16 described withrespect to FIGURE 1. On the other hand, it is contemplated in anembodiment of this arrangement of passing catalyst directly from theregeneration zone to an engaging zone 92 thereby bypassing zone 88. Inthe arrangement specifically shown in FIGURE 2 the regenerated catalystpasses through heat exchanger 88 and conduit 90 before entering engagingzone 92 about the inlet of riser 94. In engaging zone 92 there is shownintroducing a suitable inert gas such as flue gas by conduit 96. Theflue gas is combined with regenerated catalyst in engaging zone 92 toform a suspension which is thereafter passed upwardly through lift zoneor conduit 94 to a suitable separation zone 98 at the discharge end ofthe lift conduit 94. In separator zone 98 the regenerated catalyst at adesired elevated temperature is separated from the lift gas employed inlift conduit 94. The lift gas used may be a cooling gas which iseffective in achieving a partial cooling of the regenerated catalystpassed in contact therewith. It is also contemplated employinginsufficiently converted vaporous hydrocarbons in place of flue gasunder conditions which will effect a desired conversion of thehydrocarbons with simultaneous cooling of the catalyst as hereindiscussed. Positioned beneath separator zone 98 is a trim cooler zone100 pro vided to effect further cooling of the catalyst and/or strippingin the event that vaporous hydrocarbons are employed in lift conduit 94.Accordingly trim cooler 100 is positioned adjacent separator 98 and maybe used as desired to regulate the temperature of the catalyst particlesbeing passed to the conversion zone 102 hereinafter discussed. It is tobe understood that separator -98 may be a plurality of separation zonessimilar to that discussed hereinbefore with respect to separator 60, 38and 4. A plenum chamber 104 is provided across the upper cross sectionalarea of reactor chamber 102. 'In order to achieve a desired distributionof catalyst particles flowing downwardly through reactor 102 in adispersed phase condition, a plurality of open end passageways 106 areprovided which extend through plenum chamber 104 in a manner similar tothat described with respect to passageways 68. Furthermore, the bottomof the plenum chamber 104 is provided with a perforated distributorplate containing openings 108 provided for distributing hydro carbonvapors in contact with catalyst particles to form a down flowingdispersed phase mixture of catalyst in hydrocarbon vapors. The oilvapors are introduced to plenum chamber 104 by conduit 110. A separatormeans 112 provided with baflle 114 similar in configuration to thatdescribed with respect to separator 76 in the regenerator is provided inthe lower portion of the reactor zone for effecting separation ofcatalyst particles from hydrocarbon product vapors. Hydrocarbonconversion product vapors are withdrawn from separator 112 by conduit116 for passage to suitable fractionating equipment not shown. Catalystparticles separated by deflector baflle 114 and separator zone 112 arecollected in the bottom lower por tion of the reactor zone as arelatively dense mass of catalyst particles. It is to be understood thata suitable stripping gas may be introduced to the lower portion of thereactor to effect at least partial removal of entrained and adsorbedvaporous hydrocarbons from the catalyst particles. Catalyst particlesthus collected in the lower portion of reactor 102 are conveyed byconduit 118 to indirect heat exchange and stripping zone 88 whichfunctions in a manner similar to that described with respect to zone 16,FIGURE 1. Thereafter, the spent catalyst is conveyed to engaging zone 52thereby completing the cyclic flow of catalyst particles through thesystem of FIGURE 2.

In the arrangement of FIGURE 2, it is to be understood that catalystflow to the down flow dispersed phase reactor 102 and regenerator 66 maybe controlled by varying the back pressure on the cyclone. Mechanicalmeans may also be employed if preferred.

FIGURE 3 on the other hand presents an arrangement of means which may bemore suitable than that specifically described with respect to FIGURE 2for bringing reactant material in contact with solid particle material.That is, the contact zone of FIGURE 3 which may be employed either as aregeneration zone or a hydrocarbon conversion zone employs the principalof impinging a stream of hydrocarbon vapors of air against a downflowing stream of discharged catalyst particles to provide at least theinitial contact therebetween. Experimenting with this method ofcontacting was found to be very effective for obtaining contact ofgasiform material with solid contact material to form a desireddispersion for down flow through the contact zone. Accordingly, FIG- URE3 is similar to FIGURE 2 except for the manner that the gas oil feed isbrought in contact with the catalyst. Conduit 120, the gas oil feedconduit, terminates in an upwardly dis-charging L shaped nozzlearrangement 122 coaxially aligned with the bottom open end of catalystconduit 124 extending downwardly from a cooler 126. Cooler 126 issimilar to cooler 100 described with respect to FIGURE 2. The rate ofcatalyst flow in conduit 124 may be controlled by mechanical means suchas a valve either above or in conjunction with a pressure control on thereaction zone. Separator 128 above cooler 126 is similar to separator 98of FIGURE 2 and catalyst particles are withdrawn from the bottom of thevessel by a conduit 130 which is similar to conduit 118 in FIGURE 2. Aseparator assembly 132 with gasiform withdrawal conduit 134 ispositioned in the lower portion of the vessel and functions in a mannersimilar to that described with respect to 112 and 114 of FIGURE 2.

Although the arrangement specifically described herein shows differentmethods for effecting initial contact of gasiform material with solidparticle material, there are other methods and means which may besuccessively employed and it is contemplated employing any one of theseknown arrangements in the systems of this invention to achieve thedesired initial mixing or reactant material with solid particlematerial. Similarly, many different arrangements are known forseparating solid particle material from gasiform material and it iscontemplated employing these arrangements, where suitable, in thesystems of this invention.

The methods and systems hereinbefore described are of a naturepermitting considerable flexibility in their operation. Therefore, it isintended to take advantage of this flexibility in various operatingembodiments thereof to obtain, for example, per pass conversion (recycleoperations) in a range up to about 30 or 40%. Furthermore, the catalystregeneration conditions are susceptible to wide variations in operatingconditions to permit an exotherrnic temperature rise of as much as about200 degrees without causing heat damage to the catalyst. This,therefore, permits considerable variation in the amount of recycledregenerated catalyst for the purpose herein discussed and this variationaffects the permissible temper-ature in the system. It is alsocontemplated taking advantage of the catalyst heating and/ or mixingzones external to the conversion and regeneration zones to achievedesired stripping of catalyst particles to recover, for example,hydrocarbon vapors from the spent catalyst.

It will be immediately recognized from the above discussion that manymodifications and permutations may be made to the methods and systems ofthis invention without departing from the spirit and scope thereof andsuch variations may not be properly regarded as major departurestherefrom.

Having thus provided a description of the methods and systems of thisinvention and discussed specific embodiments thereof, it is to beunderstood that no undue restrictions are to be imposed by reasonthereof except as defined by the claims.

We claim:

1. A method for cracking hydrocarbons in the presence of finely dividedsolid crystalline aluminosilicate catalytic material which comprisesforming a relatively dilute suspension of crystalline aluminosilicatecatalytic material in hydrocarbon vapors at a temperature of at leastabout 850 F., passing the thus formed suspension through an elongatedconfined reaction Zone under conditions to achieve at least about 50%conversion of fresh feed, separating spent catalytic material withcarbon deposits thereon from said conversion products, combiningseparated spent crystalline aluminosilicate catalytic material with aquantity of hot regenerated catalytic material in an amount sufficientto provide a mixture of catalytic material at a temperature of at leastabout 1000 F., regenerating all of said mixture of catalytic materialwith oxygen containing gaseous material under conditions to retain up toabout 0.5% by weight of residual coke on said catalytic material withoutexceeding a temperature of about 1500 F., recycling a sufiicient portionof said regenerated catalytic material to form the above mixture withspent catalytic material at a temperature of at least about 1000 F.,cooling a portion of said regenerated catalytic material, and employingthe thus cooled catalytic material to form said relatively dilutesuspension at a temperature of at least about 850 F.

2. A method for cracking hydrocarbons which comprises form-ing asuspension of hydrocarbon vapor with catalyst particles at a catalyst tooil ratio less than about 4, said catalyst comprising a rare earthexchanged crystalline alumino-silicate combined with from about 0.1% toabout 0.5% by weight of residual coke, said suspension being initiallyformed at a temperature of at least about 950 F. and maintained in adispersed phase reaction zone for a time sufficient to obtain at least65% conversion of the fresh feed hydrocarbon vapors, separating saidsuspension after removal from said reaction zone into hydrocarbon vaporsand catalyst particles, recovering said hydrocarbon vapors, combiningsaid separated catalyst particles with suflicient hot regeneratedcatalyst particles in a dense aerated bed under condition to form amixture at a temperature of at least about 1200 F., regenerating all ofsaid mixture under conditions to limit the catalyst temperature increaseto not substantially more than about degrees, particularly cooling aportion of said regenerated catalyst particles, to form said suspensionat a temperature of at least about 950 F. with said partially cooledcatalyst particles.

References Cited UNITED STATES PATENTS 2,389,236 11/1945 Payne 208-1592,412,025 12/ 1946 Zimmerman 208-160 2,414,002 1/1947 Thomas et al.208-164 2,518,693 8/1950 Johnig 208-164 2,756,189 7/1956 Scharmann etal. 212-419 2,758,066 8/1956 Brackin 208-151 2,943,042 6/ 1960 Stokes etal. 208-127 3,140,215 7/1964 Plank et al. 208-120 3,143,491 8/1964Bergstrom 208- DELBERT E. GANTZ, Primary Examiner.

ABRAHAM RIMENS, Examiner.

1. A METHOD FOR CRACKING HYDROCARBONS IN THE PRESENCE OF FINELY DIVIDEDSOLID CRYSTALLINE ALUMINOSILICATE CATALYTIC MATERIAL WHICH COMPRISESFORMING A RELATIVELY DILUTE SUSPENSION OF CRYSTALLINE ALUMINOSILLICATECATALYTIC MATERIAL IN HYDROCARBON VAPORS AT A TEMPERATURE OF AT LEASTABOUT 850*F., PASSING THE THUS FORMED SUSPENSION THROUGH AN ELONGATEDCONFINED REACTION ZONE UNDER CONDITIONS TO ACHIEVE AT LEAST ABOUT 50%CONVERSION OF FRESH FEED, SEPARATING SPENT CATALYTIC MATERIAL WITHCARBON DEPOSITS THEREON FROM SAID CONVERSION PRODUCTS, COMBININGSEPARATED SPENT CRYSTALLINE ALUMINOSILICATE CATALYTIC MATERIAL WITH AQUANTITY OF HOT REGENERATED CATALYTIC MATERIAL IN AN AMOUNT SUFFICIENTTO PROVIDE A MIXTURE OF CATALYTIC MATERIAL AT A TEMPERATURE OF AT LEASTABOUT 1000*F., REGENERATING ALL OF SAID MIXTURE OF CATALYTIC MATERIALWITH OXYGEN CONTAINING GASEOUS MATERIAL UNDER CONDITIONS TO RETAIN UP TOABOUT 0.5% BY WEIGHT OF RESIDUAL COKE ON SAID CATALYTIC MATERIAL WITHOUTEXCEEDING A TEMPERATURE OF ABOUT 1500* F., RECYCLING A SUFFICIENTPORTION OF SAID REGENERATED CATALYTIC MATERIAL TO FORM THE ABOVE MIXTUREWITH SPENT CATALYTIC MATERIAL AT A TEMPERATURE OF AT LEAST ABOUT1000*F., COOLING A PORTION OF SAID REGENERATED CATALYTIC MATERIAL, ANDEMPLOYING THE THUS COOLED CATALYTIC MATERIAL TO FORM SAID RELATIVELYDILUTE SUSPENSION AT A TEMPERATURE OF AT LEAST ABOUT 850*F.